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02 V6 Discovery fuel gauge reading back to front - Screwloose

I wouldn't be surprised if the new sensor needs adaption to the display ECU.
02 V6 Discovery fuel gauge reading back to front - Screwloose

Forget the previous answer - not applicable to a Freeloader.

You may have got the wrong tank unit fitted. Swapping the blue wires round probably won't help.
02 V6 Discovery fuel gauge reading back to front - Screwloose

It is possible that some incorrectly-assembled tank units have been distributed. Check with your supplier.